PROJECT SUMMARY Germ cells give rise to eggs and sperm, thus eventually to a whole new organism of the next generation. The formation of germ cells is a critical step in the continuity of life for sexually reproducing organisms like humans. How do germ cells form? It remains the core question of germ cell research. Recently, it was revealed that the development of germ cells rely on a dynamic assembly of ribonucleoproteins (RNPs), germ granules. Me31B protein, a conserved component of germ granules in Drosophila (fruit fly), has been showed to interact with other germ granule proteins and contribute to germ cell formation by regulating the translation of certain germline mRNAs. Our recent study on the Me31B interactome showed that Me31B interacts with four groups of proteins in different types of ribonucleoprotein granules: RNA regulation proteins, glycolytic enzymes, cytoskeleton/motor proteins, and germ plasm components. We hypothesize that Me31B's interaction with these partner proteins as well as Me31B itself play important roles in the regulation of germ granule RNAs, which leads to proper germline development and germ cell formation. Therefore, we propose to investigate the role of Me31B in germ cell development by specifically studying: 1) Me31B Interactome in early Drosophila embryos; 2) The Recruitment Mechanism of Me31B to the Germ Granules; 3) The Mechanism and Function of Me31B-Tud Interaction; 4) The Role of Me31B in Germ Granule RNA Regulation. The proposed study will produce critical information that helps us understand how Me31B works together with its associated proteins and ultimately contributes to germ cell development. Finally, as an essential goal of Academic Research Enhancement Award program, the proposed projects will enhance the education for the undergraduate students at Indiana University Northwest by engaging them in frontline germ cell research.